Pile article



Dec. 20, 1966 C. R KOLLER PILE ARTICLE Filed Jan. 22, 1963 FIG! 2Sheets-Sheet 1 INVENTOR C HARL ES RICHARD KOLLER I BY ATTORNEY Dec. 20,1966 c. R. KOLLER 3,293,105

7 PYILE ARTICLE Filed Jan. 22, 1963 2 Sheets-Sheet 2' P ILE FIBERSADHESIVE LAYER BACKING INVENTOR CHARLES RICHARD KOLLER I @Mm ATTORNEYUnited States Patent 3,293,105 PILE ARTICLE Charles Richard Koller,Wilmington, Del., assignor to E. I. du Pont de Nemours and Company,Wilmington, Del., a corporation of Delaware Filed Jan. 22, 1963, Ser.No. 253,175 4 Claims. (Cl. 161-67) This invention relates to novel pilearticles and, more particularly, to pile articles having a uniquecombination of structural characteristics which give rise to outstandingfunctional qualities.

It is an object of the invention to provide a group of pile articlessuch as carpets, fleeces and furs, which -articles are of high quality,luxurious, and have an unusal set of aesthetics. An additional object isto provide pile fabrics having a combination of optimum performanceproperties with respect to load support, thickness recovery, bulk,cover, and insulating values. A further object of the invention involvesa critical selection of structural characteristics in producing a pilefabric so that the product will utilize the pile fibers to maximumefficiency. Other objects will be apparent from the description of theinvention given below.

This application is a continuation-in-part of copending applicationSerial No. 787,662 filed January 19, 1959, now US. Patent No. 3,085,922.

The present invention provides a pile article comprising an adhesivelayer and upstanding therefrom, at an average angle of between 45 and90, crimped synthetic organic polymeric filamentary structures alignedgenerally in the same direction having an average denier per filament dof 2 to 25, the said filamentary structures within the adhesive layerpenetrating the surface thereof in randomly spaced apart fashion andbeing anchored thereby, the said filamentary structures without theadhesive layer being characterized by: (a) forming a highly porous pilehaving a pile fiber density D between about 0.5 and 3.2 lbs./ft. havinga number of filamentary structures N between about 5,000 and 16,000 persquare inch and having a face defined by the ends of the filamentarystructures, (b) being intermingled in non-fixed touching engagement toprovide a K value of between about 1.3 and 3.0, wherein K is the rat-i0of the average extended length of the filamentary structures to theheight of the said pile, and (c) being uniformly spaced such that thestandard deviation of the number of filamentary structures per samplearea in any given plane parallel to said adhesive layer is less than0.75 times the average number of filamentary structures per sample areain that plane, wherein the sample area is of such size to contain anaverage of 5 to 25 filamentary structures, with (d) the proviso thatsaid pile fiber density bears such relation to K and d that K is atleast and d is between 2D and (14.3D3.8).

In essence the foregoing describes a unique combination of structuralcharacteristics for a pile article. Such articles which fulfill each ofthese essential characteristics will possess optimum performanceproperties with respect to load support, thickness recovery, blulk,cover and insulating value. As is apparent therefrom, the inventioninvolves not only the finding that the parameters of denier, pile fiberdensity, and K ratio must be within specified numerical ranges, but inaddition the fact that these parameters must bear a definiterelationship to one another.

As will be apparent from the detailed description given herein, a numberof the characterizing features of the products of the invention relateto fibre spacing relationships or angular considerations which appearfrom examination of the pile articles. While for practical purposesthese aspects could frequently be observed by the naked eye,particularly when the manufacturing details of the sample are known,microscopic examinations are required for precise measurements. It is tobe understood that the herein contained description is based upon suchmicroscopic examinations and that conclusions stated with respect tomanycritical features of the pile articles are in part founded thereon.In this regard FIGURE 1 is a schematic diagram at .5 X of an exactthree-dimensional model of a section of a pile article. The model, whosedimensions are 63.5 times those of the original sample, accuratelyexemplifies the space and angular considerations involved.

FIGURE 2 shows a schematic illustration of a pile fabric of theinvention as comprising a layer of upstanding pile fizers adhered to alayer of adhesive which in turn'is bonded to a backing layer.

To a large extent the above defined pile articles provide a uniquecombination of functional qualities owing to certain fiber spacingrelationships and to the amount of fiber crimp which are expressly andinherently prescribed by the recited limitations. In this regardreference is made to the following equation which taken in conjunctionwith the above mentioned numerical values and limits is useful inexpressing the relationship between certain structural characteristicsin the pile article:

93,00,0XD K- N d Therein K denotes the average degree of crimp in thefilarnentary structures, D is the pile fiber density of that portion ofthe pile above or without the adhesive layer in the fabric, N is thenumber of filamentary structures per square inch in any given section ofthe fabric which is cut parallel to the adhesive layer, and d is theaverage denier per filament of the filamentary structures.

In order to satisfy the objects of this invention, it has been foundthat the filamentary structures must be arranged in the pile portion ofthe article so-that they are intermingled, e.g. entangled with oneanother, in nonfixed touching relationship (i.e., being unbonded orother,- wise free of permanent connections) when the pile article is ina static state. This intermingled relationship is achieved by combininga certain amount of crimp in the filamentary structures together with acertain spacing be tween said structures in the pile article. If thepile fabric is prepared so that the above intermingled relationshipexists between the filamentary structures in the static state, then thepile article will be of such character that when compressed, worn, used,or otherwise placed in a dynamic state, the filamentary structuresthereof will coact in positive relationship with one another to producemore touch points than in the static state. As a consequence it willthus exhibit optimum performance with respect to load support, bulk,cover, and other properties.

One additional structural characteristic must be employed in the pilearticles in order to obtain the necessary intermingled relationship orengagement between the filamentary structures which will lead to optimumcoaction between them when placed under a load. This additionalcharacteristic involves the orientation of the filamentary structures.The pile article is formed such that an adhesive layer securely andpermanently anchors the root ends of nearly every filamentary structurein upstanding relationship from points within the adhesive layer, e.g.the filamentary structures are arranged so that the average anglethereof formed by engagement with the adhesive layer is between 45 andThe angle formed by each filamentary structure in the pile layer of theartistructures to provide a thin self-supporting sheet.

cle is determined by drawing a straight line from the root A end of eachfilamentary structure at the surface of the adhesive layer to the tipend of said structure in the face of the pile article. This straightline distance is drawn "between the two ends of each filamentarystructure as it exists in the pile article under static conditions, e.g.the straight line distance between the two ends without extending thefilamentary structure or, in other words, without pulling out any of thecrimp. The angle which this straight line distance between the endsmakes with the adhesive layer is the angle of orientation for thatparticular filamentary structure in the pile article.

Such a straight line distance L, and angle 6 are shown for a typicalfilamentary structure in FIGURE 1 of the drawings. It has been foundthat at least 85% and preferably 95% of the filamentary structures ineach pile article of this invention are positioned at an orientationangle of between 45 and 90 from the adhesive layer. Accordingly thefilamentary structures are said to be aligned in substantially the samedirection or simply aligned.

As further shown in FIGURE 1, h is the pile height, C indicates fibercross-over points, and A indicates the upper surface of the adhesivelayer.

As further described in parent application S.N. 787,- 662, one suitablemethod for preparing; the pile articles of this invention comprisesarranging in a mold a plurality of aligned crimped filamentarystructures so that the "structures have an orientation angle between 45and 90' binder composition. Upon drying to remove the vehicle orvolatiles of the binder composition, adjacent filamentary structuresbecome bonded to each other at their touch points throughout the threedimensions of the product within the mold, e.g. become attached at aplurality of spaced points along their lengths by small particles of thedried binder composition. Thereafter the walls of the mold are removedand the resulting porous fibrous block is cut transversely to thedirection of the filamentary For most pile article uses the thickness ofthe sheet will vary between about k lfl and inch. The fibrous sheets areporous layers with the top and bottom faces of each sheet being definedby the respective ends of each of the filamentary structures therein.The porous bonded sheet is then attached to an adhesive layer byapplying a continuous layer of suitable adhesive to a cut fiace of thesheet, followed by curing and/ or drying to solidify the adhesive layer.The adhesive layer can be used alone as the backing for the final pilearticle or one or more additional layers can be attached below theadhesive layer. The additional backing layer can be applied by pressingthe adhesive coated sheet while still tacky against a layer such asburlap, *a plastic film or the like, and allowing the adhesive to set.As an alternative method, the adhesive may be applied to the backingalone, or to both the backing and the cut face of the sheet prior toassem b'ling the sheet material on the backing. If desired, the adhesivelayer may support the backing. After one face of the bonded porous sheethas been attached to suitable backing, the next step is to treat theresulting laminate to remove substantially all of the binder compositioncontained in the pile layer outside the adhesive layer. In essence thebinder is used only as a temporary means of keeping the filamentarystructures in the desired spacial arrangement for purpose of cutting thesheet and attaching it to a backing. The binder composition isoriginally selected to be fugitive so that it can be readily removed inlater processing without damaging either the filamentary structures,adhesive layer, or additional backing and without greatly affecting thespacial arrangements established in the bonded sheet. Therefore, thefugitive binder should be soluble in a liquid medium which is inert tothe filamentary structures, adhesive layer and additional 'backings.Normally, the fugitive binder is removed by washing, leaching, scouringor otherwise dissolving the binder by immersing the backed bonded sheetin a suitable liquid medium, which may be aqueous or organic. Removal ofthe binder composition from these portions of the filamentary structureswhich are outside the adhesive layer does not elfect removal. of thesmall amount of binder composition which is attached to those sectionsof the filamentary structures which are embeded within the adhesivelayer.

Another method of preparing the pile articles of the invention involvesassembling a group of crimped filamentary structures into an elongatedbody or billet such that the majority of the aligned filamentarystructures are arranged at an angle of between and 90 with respect tothe longest dimension of the body or billet. After the assembly offilamentary structures has been 'formed, shaped or otherwise arrangedinto a body so that the structures are intermingled in touchingarrangement, the body is impregnated with a fugitive binder compositionthroughout the interstices of the body, and then the excess binder isallowed to drain out followed by drying to leave only small particles ofbinder attaching the structures together at their contact points.Alternatively, the assembly of intermingled filamentary structures maybe sprayed on the outside of the assembly with a fugitive bindercomposition to attach together only the filamentary structures on theperiphery of the body, leaving the interior structures unattached.Several of these bodies or billets are then sliced-transversely to thelongest dimension of the body into thin discs or wafers, each of thesebeing characterized by two out faces at either end with the cut facescontaining the two ends of each filamentary structure. Thereafter anumber of these discs are attached to an adhesive layer by using asuitable adhesive composition as described above. For this purpose anumber of the discs may be placed in side-by-side contact with thelongitudinal axes thereof parallel to each other. Such parallelrelationship is maintained by placing the discs in a mold or otherholding means so that one cut face of each is exposed during theapplication of adhesive composition to all of the fiber ends in one ofthe face which is formed. The continuous adhesive layer is then cured,dried, or otherwise solidified. Again one or more additional backinglayers may be appropriately incorporated into the product. Subsequentlythe resulting laminate 'may be washed or otherwise treated as indicatedabove to remove the fugitive binder remaining on that portion of thefilamentary structures without the adhesive layer. The resulting pilearticle is composed of a continuous adhesive layer with an upstandingpile composed of filamentary structures which are intermingled innon-fixed touching arrangement;

The pile articles of the invention can be prepared batchwise or in acontinuous manner starting with a variety of filamentary structures. Thefilamentary structures must have a certain amount of crimp, as morefully described below. However, they may be prepared from carded webs ofstaple fibers or from a warp of sliver, top, roping, roving, tow, steambulked tow, steam crimped continuous filament yarn, gear crimpedcontinuous filament yarn, twist set-backed twisted continuous filamentyarn, knife edge crimped continuous filament yarn, spun yarns,continuous monofilaments, continuous multifilaments, or any other formof filamentary structure which possess a three-dimensional crimp orcurvilinear contortion between the ends of sufficient magnitude tofulfill the quantitative requirements specified below. The fibers andfilaments may be bulked or unbulked, drawn or undrawn, or twisted oruntwisted, and may be of round cross section or may have a cross sectionof other different geometry,

such as trilobal, tetralobal, pentalobal, elliptical, ribbon shaped,crescent shaped, and the like.

The synthetic organic polymeric filamentary structures for use in thisinvention can be made from a wide variety of compositions, typical ofwhich include those made of polyamides, such as poly(hexamethyleneadipamide), poly(meta-phenylene isophthalamide), poly(hexamethylenesebacamide), polycaproamide, copolyamide and irradiation graftedpolyamides, polyesters and copolyesters such as condensation products ofethylene glycol with terephthalic acid, ethylene glycol with a 90/10mixture of terephthalic/isophthalic acids, ethylene glycol with a 98/2mixture of terephthalic/S-(sodium sulfo)-isophthalic acids, andtrans-p-hexahydroxylylene glycol with terephthalic acid, self-elongatingethyleneterephthalate polymers, polymerized hydroxypivalic acid,polyacrylonitrile, copolymers of acrylonitrile with other monomers suchas vinyl acetate, vinyl chloride, methyl acrylate, vinyl pyridine,sodium styrene sulfonate, terpolymers ofacrylonitrile/rnethylacrylate/sodium styrene sulfonate made inaccordance with US. Patent 2,837,501, vinyl and vinylidene polymers andcopolymers, polycarbonates, polyacetals, polyethers, polyurethanes,polyesteramides, polysulfonamides, polyethylenes, polypropylenes,fluorinated and/ or chlorinated ethylene polymers and copolymers (e.g.polytetrafluoroethylene, polytrifluorochloroethylenes), cellulosederivatives, such as cellulose acetate, cellulose triacetate, compositefilaments such as, for example, a sheath of polyamide around a core ofpolyester as described in U.S. 3,03 8,236 to Breen, and self-crimpedcomposite filaments, such as two acrylonitrile polymers differing inionizable group content cospun as described in US. 3,03 8,237 to Taylor.Preferred materials are those composed of linear polymers and especiallythose wherein the polymer has an initial tensile modulus above 2 gramsper denier. Blends of two or more synthetic fibers can often be used toadvantage.

The binder employed for temporarily attaching together the filamentarystructures during the preparation of the unbonded pile fabrics of theinvention must be fugitive, e.g. be selected so that they can be readilyremoved from the pile layer. Normally, a binder composition should beselected which is soluble in aqueous medium or in organic medium. Suchmedium should be essentially inert to the filamentary structuresemployed as well as to the adhesive layer and any additional backinglayers which may be provided before removal of the binder. Examples oftypically suitable binder compositions include polyacrylic acid, acrylicacid copolymers, and polyvinyl alcohol, all of which are water soluble.Examples of suitable alcohol soluble binders include the terpolymersformed by condensing together caprolactam, hexamethylene diamine, adipicacid and sebacic acid such that there are substantially equalproportions of polycaproamide, polyhexamethylene adipamide andpolyhexamethylene sebacamide in the terpolymer. Other suitable organicsolvent soluble binders include natural rubber or synthetic elastomers,these then being used in the form of a latex dispersion, emulsion, or inthe form of a solution. Still other organic solvent soluble binders areacrylic and methacrylic ester copolymers, methoxymethyl polyamides andvarious vinyl resin polymers and copolymers.

A wide variety of materials can be employed to form the adhesive layerto which the filamentary structures are to be attached. By adhesive orglue or cement is meant the material used to cause the root ends of thefilamentary structures to adhere to one or more backing layers, or ismeant the material used to constitute the backing. Illustrativeadhesives include: chloroprene rubber, elas-tomeric foams and sponges,butadiene-styrene rubber, polyvinyl chloride resin (e.g., those incombination with either a polymeric plasticizer or a monomericplasticizer curable after application of the adhesive), polyvinylacetate resins, polyurethane resins, polyamide copolymer ofhexamethylene diamine and adipic and sebacic acids, casein resins, andepoxy resins such the reaction products of epichlorohydrin of2,2-bis(parahydroxyphenyl)propane. For most purposes an adhesivematerial Will be chosen which can be cured to a thermoset condition.Illustrative backings include: woven fabrics such as burlap, canvas, andnylon scrim fabrics, knit fabrics such as nylon tricot, non-wovenfabrics such as polyethylene or polypropylene fiber webs, resin bondedpolyethylene terephthalate fiber webs, papers of cellulosic and/orsynthetic fibers, paper felts such as asphalt impregnated cellulose,elastomeric foams and sponges, plastic films such as from polyethyleneterephthalate, polypropylene and polyvinyl chloride polymers, metalfoils and rigid sheets such as fiber glass reinforced polyester resins,metals, ceramics and wood, elastic, stretchable or shrinkable fabricsand films, and the like.

The superior performance properties experienced with the products ofthis invention directly depend from the maintenance of criticalstructural parameters within the ranges of values and relationshipsgiven above. Although the reasons for superior performance are not fullyknown, it is believed that the following pertinent considerationsconstitute at least a partial explanation. In the products of thisinvention the fibers are aligned more nearly perpendicular to thebacking than parallel to it; as a result, when the pile is compressed byapplication of a load the fibers buckle or bow, each fiber buckling in apreferred direction. The fiber segments, which are randomly oriented,contact segments of neighboring fibers and oppose their motion. Thelarge number of contacts, or near contacts, in the structure, e.g. seepoints C in the drawings, as made insure that a fiber will interferewith neighboring fibers irrespective of the direction of its movement.At the beginning of buckling the lateral forces are weak. If fibers areplaced close to each other, they will contact at the start of buckling,the weak lateral forces will be overcome, and a group of fibers willfollow the direction preferred by the majority. Fibers bending inparallel do not provide maximum load support. At lower pile densities,the fibers are spaced farther apart and develop strong lateral forces"before touching. Each contact remains fairly stationary during thefurther compression; the result is that portions of a fiber on eitherside of a contact point bend independently. This shortening of thebending length leads to increased pile stiffness, or increased loadrequired for a given compression. The efficiency, or load borne perfiber, is then greater than it is for an isolated fiber or for moreclosely spaced fibers. If the fibers are quite far apart, the pile canbe compressed a great deal before the mutual support of fibers makesitself felt; the efiiciency will be low. If the fiber spacing is notuniform, the advantages of this invention will not be realized, because,even if the average density is in the preferred range, the regions ofvery high and very low density will both be ineflicient for reasonsgiven above. It is thus significant that low pile fiber densities can beso utilized that not only are savings in cost realized but also thatsuperior functional qualities are afforded.

With respect to the nature and function of the adhesive layer whichbonds the filamentary structures at their root ends in the pile article,it is significant that these contribute greatly to the overallperformance properties. In particular the spacial distribution of thefibers below the glue line, e.g. below the surface of the adhesive asindicated by point A in the drawings, does not differ significantly fromthe distribution of fibers without the adhesive layer. Essentially eachfiber penetrates the surface of the adhesive in randomly spaced apartfashion and is anchored therein. Because the root end of nearly everyfiber extends within the adhesive and is separated from the root ends ofadjacent fibers, the adhesive can contact the entire surface thereof andfirmly secure it in a fixed position; thus shedding problems can beessentially avoided. Aside from the functional benefits which occur byvirtue of this adherent relationship, it is significant that improvedeconomies are afforded because only very minor quantity of fibersections do not contribute to the aesthetics of the pile article.

A more complete characterization of the structural features in the pilelayer of the products of this invention will now be given.

At least 80% of the tip ends of the filamentary structures, i.e. thoseforming the face of the pile fabric, are positioned at least 0.8 timesthe pile height it above the adhesive layer. The more preferred pilearticles of this invention are those in which essentially .all of thetip ends of the filamentary structures reach the face of the pile. Whatthis means is that for optimum properties the greatest majority ofcrimped fibers should extend to essentially the same height above theadhesive.

Another critical structural characteristic of the pile layer is that thefilamentary structures must have a threedimensional crimp between thetwo ends of each filamentary structure. The amount of crimp orcontortion between the two ends may, in part, be characterized byspecifying K, which is defined as the ratio of the average extendedfiber length (the length of a given fiber after pulling out all of thecrimp) to the pile height h. Another measure of the amount of crimp ineach filamentary structure may be specified in terms of the crimpfrequency, which preferably should have a minimum average value of about6 crimps per inch. The crimp frequency can be determined by countingunder a magnifying glass the number of crimps along the length while thefilament is maintained at its relaxed length. Another measureof theamount of crimp between the ends of each filamentary structure may beexpressed in terms of crimp index, which should be at least 20%. Thecrimp index is defined as the difference in length between a fiber incrimped and in uncrimped condition expressed as a percentage of theuncrimped length.

An additional characteristic of the filamentary structures in the pilelayer of the preferred products of this invention is that no adjacentfilamentary structures run parallel for more than one quarter of theirlength. Still another feature of the pile layer is that the filamentarystructures contact adjacent structures on an average of at least 40times per inch of pile height h. Considering these factors, the wordsintermingled or entangled are an apt description of the engagementbetween adjacent filamentary structures. Typical examples of threedifferent types of suitable three dimensionally crimped filamentarystructures include the following:

(1) The random, three dimensional, curvilinear crimped fibers describedin Belgian Patent 573,230. More specifically filaments having this typeof crimp can pos sess alternate S and Z twist sections throughout theirlength, and have a random number of turns between twist reversals, arandom continuously varying angle of twist along their length, a randomnumber of twist reversals per inch, at least one S turn and at least oneZ turn per inch which have a twist angle averaging at least a randompersistent threedimensional, helical, curvilinear crimped configurationcontinuously along their length which may or may not be substantiallyfree from crunodal loops.

(2) The three-dimensional helical crimp described in Kilian US. Patent3,050,821.

(3) The three-dimensional crimp possessed by the composite filamentsdescribed in Taylor US. Patent 3,038,237.

As will be apparent from the above, three-dimensionally crimped fibersare necessary. In order to determine the three-dimensional character ofsuch fibers it is helpful to plot the projection of the fiber within aplane parallel to the adhesive layer as viewed from above. Thethree-dimensional character will be reflected in the area of aparallelogram which circumscribes the projection in that plane and hencedefines the two dimensional crimp amplitude of the fiber. The averagearea of the circumscribing parallelogram of the fiber projections is atleast as great as the average area occupied by the number of fiberswhich is equal to 8 times the pile density. On the average, thenarrowest dimension of the parallelogram should be at least 0.25 timesthe widest dimension.

Another critical structural requirement for the pile layer in theproducts of this invention relates to uniformity of spacing between thefilamentary structures. That is, filamentary structures should be spaceduniformly from each other at their root ends where they are attached tothe adhesive layer, as well as throughout substantially the entire pileheight h. It has been found that in order to obtain the optimumcompressional and other properties in the pile structures of thisinvention, it is necessary that the filamentary structures be spaced sothat the standard deviation, 0', of the number of fibers per sample areain any plane parallel to the adhesive layer be less than 0.75 times theaverage number of fibers per sample area. Pile layers which fulfill thislimitation with respect to standard deviation do not have localizedareas of high fiber density and low fiber density near the glue line aswould be the case with tufted pile articles.

Uniformity of fiber distribution The measurement of uniformity startswith an accurate plot of the relative positions of all the fibers whichpass through a plane approximately parallel to the backing. The plot maybe obtained by any one of a number of methods: (1) The pile fabric maybe immersed in a polymerizable compound such as butyl methacrylate, thecompound may be polymerized to a tough plastic, and the plastic may becut into thin slices parallel to the backing by means of a microtome.Enlarged photographs of some of the slices may then be taken with thehelp of a microscope; on the photographs (enlarged further if necessary)one will see the ends of all the fiber segments which pass through theslice. (2) With the help of an optical instrument such as the NikonComparator, and without slicing the fabric, one may measure thepositions of the fiber segments crossing a given plane; using theinstrument readings, one may then plot the positions on graph paper.

If the results are to be meaningful, the total area to be analyzed in agiven plane must contain at least 500 fibers. If the fibers giveevidence of being segregated into yarns or bundles, the total area mustcontain a number of fibers equal to at least six times the averagenumber of fibers per bundle.

For the analysis the total area? chosen is ruled into a grid of squaresof equal size. (This ruling into small sample areas will greatlyfacilitate counting the total number of fibers.) The average number offibers per square and the standard deviation, a, of the distributioninto squares are determined by Well-known routine methods. The averagenumber of fibers per sample area must lie between 5 and 25, and at least20 sample areas should be counted in the total area.

Pile fabric compression test Specimens measuring 4" x 4" are taken frompile fabric samples to be tested. Two specimens are normally taken fromeach sample and the data reported are the average of results from both.The specimens are conditioned in two steps according to common textiletesting procedures wherein a pre-conditioning at i10 F. in moving airfor a minimum of two hours is followed by a final conditioning at 65% RHand 70 F. in moving air for a minimum of sixteen hours. The conditionedspecimens are weighed to the nearest 0.01 gram and measured to thenearest 0.02 inch taking an average of three measurements in both lengthand width.

Each specimen mounted on a compression cell is subjected to compressionwith pile side up at the rate of 0.2

9 inch/minute on an Instron Tester using a circular presser foot of 10in.

The load cycling controls of the tester are set so as to cause thecrosshead to return when the desired full load has been applied. In thecase of carpets of high denier fiber (1225 d.p.f.), a maximum load of 10p.s.i. is used; whereas for fleeces and lower denier fiber (2-12d.p.f.), the maximum load is 1.1 p.s.i. The crosshead stops when thepressure has returned to Zero. After a two-minute interval a secondcompression cycle is run in the same manner. Following the second cycleof compression and unloading, the specimen is taken from the tester andthe pile is sheared off as evenly and cleanly as possible from thesurface of the adhesive using heavy duty barber clippers equipped with aNo. 000 (fine) clipper head. The sheared backing is then weighed to thenearest 0.1 gram. The sheared backing is subjected to compressiontesting in the same manner as in the unsheared form except that it isloaded at a rate of 0.1 inch/minute crosshead speed. During thecompression test the stress is recorded and appears on the chart as apen line whose coordinates are stressed in lbs. and separation betweencell and presser foot in inches. From this graphic data, specific pointscan be extracted. On the first compression cycle, a specific point ofinterest is the cell presser foot separation when the presser footbarely touches the sample and the pressure starts to increase. Thisseparation is used as the initial thickness of the specimen. From thesecond cycle and its record, the integrator count for the load portionof the cycle is obtained.

Other tests and measurements The pile height h of the pile fabric is theheightof the shearable fibers above the adhesive line. The pile heightin inches is obtained by subtracting the initial thickness of theadhesive and any backing layers from the initial thickness of thespecimen, both measured on the first compression cycle as indicatedabove. In the sample depicted in the drawings, 11 would be equal to thevalue of H less the thickness of the adhesive layer.

The pile weight in ounces per square yard of the fibers in the specimenis calculated by subtracting the weight of the sheared backing from thetotal weight of the unsheared conditioned specimen, and then dividingthe net weight expressed in ounces by the area (lengthxwidth) of theconditioned specimen in square yards.

The pile fiber density (sometimes called pile density herein) reportedin pounds per cubic foot is a measure of the density of the fibers inthe pile layer above the adhesive layer. The pile fiber density iscalculated by dividing the pile weight of the fibers in the pile layerby the volume these fibers occupy when the specimen is under no load.This volume is determined by multiplying the average Width by theaverage length of the conditioned specimen by the pile heigth h and thenapplying suitable conversion factors to obtain the volume in units ofcubic 'feet.

The work-to-compress of the pile fabric specimen to the point of maximumload is calculated from the second compression cycle by measuring thearea under the stressstrain curve for the second load cycle andmultiplying this by the value of inch lbs. per unit area of the chart.This value is then divided by the area in square inches of the presserfoot to provide the value in units of inch lbs./in.

The specific volume of the pile layer at a given load is calculated asthe volume of the pile at the given load divided by the pile weight. Thepile volume at the given load is determined from the second compressioncycle as the difference between the thickness of the pile fabric and thebacking at the given load times the specimen area, suitable conversionfactors being applied.

One of the chief advantages of this invention is that by following thecritical structural specifications as taught herein, it is possible toproduce pile articles having maximum compressional properties (e.g.,load support), bulk, cover, and insulating value. In this regard, carpetstructures prepared in accordance with the invention usually have aspecific volume of at least 7.0 cc./ gram at 3.1 p.s.i. and awork-to-compress to 10 p.s.i. value of at least 0.1 plus (0.025 timesthe effective pile weight expressed in oz./yd. The pile fabrics of thisinvention have a high luxurious set of aesthetics which are pleasing tothe eye as well as to the hand. As is apparent from the numerousreferences thereto in this description, the invention is particularlyapplicable for pile articles to be used as floor coverings, such ascarpets, and the like. Nevertheless such articles also find applicationfor other uses where retention of bulk is a significant factor, e.g., asfleeces, blankets, coating and suiting interliners, brushes, paint andink rollers, bufling, polishing and scouring pads, upholsteryfabrics,-and the like.

The pile layers of the products of the invention preferably consistessentially of the filamentary structures, e.g., minor amounts ofmaterials such as dyes, pigments, stabilizers, antistatic agents and thelike may be included which, either distributed within or on the surfaceof the filamentary structures, do not appreciably affect structuralcharacteristics or impair the desired properties. From the volumestandpoint, air will be the dominating component of the highly porouspile layer, usually to the extent of 90% or more. Further in this regardit will be ap parent that the products of the invention can be soprepared or otherwise treated, e.g., stylized such as sculptured orembossed that minor deviations from the defined characteristics andrelationship may exist in small localized areas without significantlyaffecting the overall properties of the product.

The average denier per filament d of the products of the invention is inthe range of 2 to 25. Alternatively this range may be expressed'as 0.2to 2.8 Tex. For carpets and other floor covering purposes, whichconstitute a preferred embodiment of the invention, the average denieris 12 to 25.

The following examples are given to illustrate the invention, but arenot intended to limit it inany manner.

EXAMPLE I Steam-bulked continuous-filament polyhexarnethylene adipamideyarn (3700 denier, 204 filaments, /2 Z twist and having a Y crosssection), prepared according to Example 2 of Belgian Patent 573,230, iscreeled into Warp sheets of aligned yarns about 30- inches wide x 3inches thick x 16 feet long. These warps are pleated into .a metal mold,30 inches long x 30 inches wide x 12 inches deep having an open top andbottom, in such a manner that the folds of the pleats extend above andbelow the mold and the fibers are essentially all aligned in a directionrunning from top-to-bottom of the mold. The pleated yarnprotruding fromtop and bottom of the mold is trimmed off, leaving approximately 14 lbs.of fiber in the mold. Two perforated metal screens are placed over thetop and bottom of the mold, and cover plates fitted with inlet .andoutlet pipes are attached, using air-tight gaskets, to the top andbottom of the mold over the screens. The binder'used in this experimentis an alcohol soluble terpolymer formed by condensing togethercaprolactam, hexamethylene diamine, adipic acid and sebacic acid, suchthat there are substantially equal molar proportions of caproamide,hexamethylene adipamide and hexamethylene sebacamide units in theterpolymer. A solution of 4% by weight terpolymer in /20 alcohol/ watermixture by volume is drawn through the mold from bottom pipe to top pipeby means of suction applied to the top pipe and allowed to drain backthrough the mold out the bottom pipe by gravity so that the contact timeof binder with fibers is about 5 minutes. Hot dry compressed air (300F.) is passed through the mold from top to bottom until all the volatilematter is removed from inside the mold. The mold is then disassembled,leaving a dry porous block consisting of fibers, binder polymer and air.The block is composed of the bulky fibers, all of which run essentiallyfrom the bottom to the top surface, the block having a fiber density of2.5 lbs/cu. ft. and a binder density of 0.17 lbs/cu. ft. The block ispassed through a horizontal band knife such that the knife blade passesperpendicular to the direction of the fibers in the block, and sheets A/8, and A inch thick are obtained, the faces thereof being definedessentially by fiber ends. The sheets are cemented to rubber-impregnatedburlap backing with a rubber-base adhesive, the binder is removed bywashing in ethanol/ water (80/20 by volume), and the resulting pilefabric is dyed with a disperse type dyestutf. This pile fabric exhibitshigh load support, good cover, pleasing aesthetics and is suitable foruse as a carpet.

By this process a product having the following characteristics isobtained:

D 2.5 lbs/cu. it.

N 9270/sq. in.

File height, h A inch.

Fiber angle Average, 79; range,

Average number of fiber contacts/ in. of pile fiber height 61. Averagehorizontal component 0.67 h.

Two-dimensional crimp amplitude 0.0029 sq. in. (area (average area ofparallelogram) occupied by 27 fibers). Average length of parallelogram0.074 inch. Average width of parallelogram 0.038 inch.

Uniformity of spacing:

Total area =analyzed=0.0944 sq. in.=approximately A in. x in. A. Asdetermined in. above the backing (877 Helically crimped polyethyleneterephthalate staple fibers prepared according to U.S. Patent 3,050,821having a 2% inch staple length, 4 denier per filament, 27% crimp indexand 7 crimps/inch are carded into a 300 grain/yard sliver on a worstedcard. Six-inch lengths of this sliver are assembled in a side-by-sidearrangeiment so that the fibers :are aligned in the same generaldirection and then compressed laterally to a density of 0.7 l-bs./ft.This assembly is placed in a 10" x 10" x 6" deep perforated metal moldso that the fibers are directed toward the mold faces (10" x 10" faces).The mold is immersed in a 6% solution of polyaorylic acid dissolved inan acetone/water mixture (3/1 ratio by volume). The mold is removedslowly and excess solution is allowed to drain from the mold. The moldis heated at 220 F. in a hot air oven to remove the solvent and solidifythe binder. The bonded fiber assembly is removed from the mold andsliced with a horizontal band knife cutter transverse to the fibers andin a plane parallel with the face of the block to give 10" x 10" x 7thick bonded fiber sheets with the fiber ends located in the sheetfaces. A sprayed coating of 1.2 oz./sq. yd. of a polyurethane adhesiveis applied to one face of a thick bonded sheet which is then cemented tothe face of a woven cotton fabric. This assembly is held together underslight pressure and heated at 240 F. for 30 minutes to bond the fiberends in one face of the sheet to the cotton backing. This product iswashed in warm water to remove the binder and tumble dried.

There is obtained a soft, drapable pile fabric suitable for use as apile lining for slippers. T-his pile fabric is found to have a specificvolume at 0.34 psi. load of 31.0 cc./gm. The pile layer is found to havean average of 8,600 fibers per sq. inch, a pile fiber density of 0.8lbs/ita an average fiber denier per filament of 4 and an average K valueof 2.14. The average number of fibers per sample area is 13.4, thestandard deviation, 0', of the number of fibers per sample area is 4.7and the ratio of th estand'ard deviation to the average number of fibersper sample area is 0.35, determined on a total of 40 sample areas.

EXAMPLE III Bicomponent polyacrylonitrile staple fibers preparedaccording to US. Patent 3,038,237 having a 2 /2" staple length and 3denier per filament were treated in hot water (190 F.) for 15 minutesand dried at F. in a tumble drier. These fibers having a crimp index of24% and a crimp frequency of 11 crimps per inch are carded into a grainsliver on a worsted card. This sliver is cut into 6 inch sections, thesections are stacked in a mold and formed into a bonded fiber assemblyhaving a fiber density of 1.0 lb./ft. the bonded block is sliced into Ain. thick sheets, and a sheet cemented to one face of a cotton fabric asdescribed in Example II. The binder is washed out of the pile layer andthere is obtained a soft bulky fabric suitable for use as :a pile liningfor garments. The pile layer of this fabric was found to have a specificvolume at 0.34 p.s.i. of 32.6 cc./gm., an average number of fibers persquare inch of 14,300, a pile fiber density of 0.99 lb./ft. a denier perfilament of 3' and a K value of 2.15. The average number of fibers persample area is 22.2, the standard deviation, 0', of the number of fibersper sample area is 6.3, and the ratio of the standard deviation to theaverage number of fibers per sample area is 0.28, determined on a totalof 40 sample areas.

EXAMPLE IV Steam bulked continuous filament polyhexaniethylene adipamideyarns of about 3700 denier (each yarn containing 204 fibers of 18 denierper filament), prepared according to Example 2 of Belgian Patent573,230, are formed into skeins having about 90 yards/skein. Each skeinis cut transverse to the fibers into 6 inch long sections which areassembled side-by-side and compressed laterally to form a 10 x 10" x 6"assembly of yarns oriented in the same direction at a density of 1.6lbs/ftfi. This assembly is bonded with a polyacrylic acid binder andsliced into /3 inch thick sheets as in Example H. One face of thesesheets is cemented to a burlap fabric using a polyurethane adhesive. Thebinder is removed from the pile layer by washing in water and the pilefibers dyed with a disperse type dyestuff. There is obtained a resilientpile fabric suitable for use as carpeting. The pile layer is found tohave a specific volume of 9.3 cc./ gm. at 3.1 p.s.i. load in the PileFabric Compression Test. The pile layer is found to have an average of5,400 fibers per sq. in., a pile fiber density of 2.1 lbs./ft. anaverage denier per filament of 1 8 and a K value of 1.98. The averagenumber of fibers per sample area is 8.4, the standard deviation, (1, ofthe number of fibers per sample area is 4.6, and the ratio of thestandard deviation to the average number of fibers per sample area is0.55, determined on a total of 40 sample areas.

1 3 EXAMPLES V-XI A series of pile fabrics of this invention wereprepared in accordance with the above examples. The fabrics in ExamplesV through X were prepared using the general procedure described inExample IV, whereas the fabric of Example XI was prepared according tothe procedure described in Example II. The seven pile fabrics arecharacterized by the following structural features and exhibit theindicated properties. The specific volume of the fabrics in Examples Vthrough X was determined under 3.1 psi. load, whereas the specificvolume of the fabric in Example XI Was determined at 0.34 p.s.i. Thedata given for the uniformity of fiber distribution Was determined on atotal of 40 sample areas.

14 between about 5,000 and 16,000 per square inch and having a facedefined by the ends of the filamentary structures, (b) beingintermingled in non-fixed touching engagement to provide a K value ofbetween about 1.3 and 3.0, wherein K is the ratio of the averageextended length of the filamentary structures to the height of the saidpile, and (a) being uniformly spaced such that the standard deviation ofthe number of filamentary structures per sample area in any given planeparallel to said adhesive layer is less than 0.75 times the averagenumber of filamentary structures per sample area in that plane, whereinthe sample area -is of such size to contain an average of 5 tofilamentary structures, with (d) the proviso that Example Fiber (1 D(lbs/It Sp. Vol. m/g

Pplyaerylo Polypropylene. Polyacrylonitrile s ps e s oowwcnw Aver. No.fibers/sample 0' area a/aver. no. fibers What is claimed is:

1. A pile article comprising an adhesive layer and upstanding therefrom,at an average angle of between 45 and 90, crimped synthetic organicpolymeric filamentary structures aligned generally in the same directionand having an average denier per filament d of 2 to 25, the portions ofsaid filamentary structures Within the adhesive layer penetrating thesurface thereof in randomly spaced apart fashion and being anchoredthereby, the portions of said filamentary structures without theadhesive layer being characterized by: (a) forming a highly porous pilehaving a pile fiber density D between about 0.5 and 3.2 1bs./ft. havinga number of filamentary structures N said pile fiber density bears suchrelation to K and d that K is at least References Cited by the ExaminerUNITED STATES PATENTS 5/1944 Bodle 16167 X 1/1962 Tlaylor 161-177 X4/1963 Koller 16167 JACOB H. STEINBERG, Primary Examiner. MORRISSUSSMAN, EARL M. BERGERT, Examiners.

0.9 1+ D
 1. A PILE ARTICLE COMPRISING AN ADHESIVE LAYER AND UPSTANDINGTHEREFROM, AT AN AVERAGE ANGLE OF BETWEEN 45* AND 90*, CRIMPED SYNTHETICORGANIC POLYMERIC FILAMENTARY STRUCTURES ALIGNED GENERALLY IN THE SAMEDIRECTION AND HAVING AN AVERAGE DENIER PER FILAMENT D OF 2 TO 25, THEPORTIONS OF SAID FILAMENTARY STRUCTURES WITHIN THE ADHESIIVE LAYERPENETRATING THE SURFACE THEREOF IN RANDOMLY SPACED APART FASHION ANDBEING ANCHORED THEREBY, THE PORTIONS OF SAID FILAMENTARY STRUCTURESWITHOUT THE ADHESIVE LAYER BEING CHARACTERIZED BY: (A) FORMING A HIGHLYPOROUS PILE HAVING A PILE FIBER DENSITY D BETWEEN ABOUT 0.5 AND 3.2LBS./FT.3$, HAVING A NUMBER OF FILAMENTARY STRUCTURES N BETWEEN ABOUT5,000 AND 16,000 PER SQUARE INCH AND HAVING A FACE DEFINED BY THE ENDSOF THE FILAMENTARY STRUCTURES, (B) BEING INTERMINGLED IN NON-FIXEDTOUCHING ENGAGEMENT TO PROVIDE A K VALUE OF BETWEEN ABOUT 1:3 AND 3.0,WHEREIN K IS THE RATIO OF THE AVERAGE EXTENDED LENGTH OF THE FILAMENTARYSTRUCTURES TO THE HEIGHT OF THE SAID PILE, AND (C) BEING UNIFORMLYSPACED SUCH THAT THE STANDARD DEVIATION OF THE NUMBER OF FILAMENTARYSTRUCTURES PER SAMPLE AREA IN ANY GIVEN PLANE PARALLEL TO SAID ADHESIVELAYER IS LESS THAN 0.75 TIMES THE AVERAGE NUMBER OF FILAMENTARYSTRUCTURES PER SAMPLE AREA IN THAT PLANE, WHEREIN THE SAMPLE AREA IS OFSUCH SIZE TO CONTAIN AN AVERAGE OF 5 TO 25 FILAMENTARY STRUCTURES, WITH(D) THE PROVISO THAT SAID PILE FIBER DENSITY BEARS SUCH RELATION TO KAND D THAT K IS AT LEAST